We examine the nutritional status of a cohort of poor Ethiopian children and their patterns of catch-up growth in height-for-age between three key development stages: age one, five and eight. We use ordinary least squares (within community) and instrumental variables analysis. During the earliest period, we find that nutritional catch-up patterns vary substantially across socioeconomic groups: average catch-up growth in height-for-age is almost perfect among children in relatively better-off households, while among the poorer children, relative height is more persistent. Between five and eight years of age, however, we find near-perfect persistence and no evidence of heterogeneity in catch-up growth. Our findings suggest that household wealth, and in particular access to services, can lead to substantial catch-up growth early on in life. However, for our sample, the window of opportunity to catch up appears to close as early as the age of five.